Chronic congestive heart failure (CHF) in children represents a final common pathway resulting from congenital or aquired heart disease. Despite standard therapy with digoxin, diuretics, and angiotensin converting enzyme inhibitors, many children eventually require heart transplantation to prolong survival. Adrenergic blockade has been employed in adults suffering from congestive heart failure with resultant decreased morbidity and mortality. Because of these promising results in adults, we propose to examine the effects of labetalol, a nonselective beta-and selective alpha-1 adrenergic blocking agent, in the treatment, we intend to obtain exercise tolerance tests, electrocardiograms, and echocardiograms in 20 children before treatment, after 4 and 6 months of maintenance therapy, and again 2 weeks after labetalol therapy has been discontinued. The significance of this study is the potential for the development of new approaches to the treatment of chronic CHF in children. The use of labetalol in this setting has the potential to improve cardiac function, improve the quality of life, prolong survival, reduce medical care costs, and postpone or preclude the need for heart transplantation.